Exhibit 32.1

Section 1350 Certifications

Pursuant to 18 U.S.C. § 1350 as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, each of the undersigned officers of Isoray, Inc., a Delaware corporation (the "Company"), hereby certify that:

To my knowledge, the Quarterly Report on Form 10-Q of the Company for the quarterly period ended March 31, 2022 (the "Report") fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Dated: May 12, 2022

 /s/ Lori A. Woods

Lori A. Woods

Chief Executive Officer
(Principal Executive Officer)

/s/ Jonathan Hunt

Jonathan Hunt

Chief Financial Officer
(Co-Principal Financial Officer)

/s/ Mark J. Austin

Mark J. Austin

Vice President of Finance and Corporate Controller
(Co-Principal Financial Officer, Principal Accounting Officer, Corporate Secretary)